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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Android-Based Information Synchronization in Social Networks

Ji, Yu-Shin 26 July 2010 (has links)
In the beginning, computers are developed in need of complex computing. And it has been evolved from mainframes in enterprise and computer center to desktop at home. After the rapidly spreading of internet, computer undertakes an important role in people¡¦s life. It helps us with our work, doing computation, even links people together through E-mail and instant message software. With computers by our side, we live a much more convenient life. Google announced its latest mobile platform operating system ¡§Android¡¨ on November 5th, 2007. Android is constructed base on Linux kernel, which means it can be treated as a portable computer, with application designed for entertaining, Internet surfing, and social communication. Social communication has been proven to be a important issue. For instance, Facebook, a social network service provider online since February 4th, 2004, creates a place to let people share their messages, photos and news, has more than ten million user today. So far the mobile phone has become a very convenient way to communicate, but if users wish to share photos, music or documents to friends. This thesis is going to discover a new way to share views, photos, music with friends immediately. This paper describes the issues with data synchronization between mobile phones.

A Hybrid Data Acquisition Architecture on the CH-53K Program

Dehmelt, Chris 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / As today's flight test programs need for sensor and bus data continue to increase, there has been associated requirements to provide modern system output products and support higher encoder data rates. The CH-53K Heavy Lift Replacement (HLR) Program is an example in which the instrumentation data requirements have increased significantly over previous helicopter programs and necessitated the introduction of new technologies and capabilities. The CH-53K Program utilizes a hybrid system architecture that combines the benefits of legacy PCM and modern networked system architectures. The system provides for maintaining the required system-wide synchronized sampling capabilities, while providing real-time data access and system control over a vehicle network. Serial Streaming Telemetry (SST)-to-vNET Adapters are employed to enable many of these capabilities. This paper describes the instrumentation requirements for the CH-53K program and the features, tools and performance of its data acquisition system - which addressed all requirements while minimizing the overall impact to the existing instrumentation infrastructure.

Signal-to-noise ratio gains and synchronization requirements of a distributed radar network

Hurley, Sean M. 06 1900 (has links)
This thesis explores the potential benefits of two, three, and four-node distributed radar networks with the potential to provide a received SNR proportional to n2 times that of a single-node system, where n is the number of nodes in the network. By plotting the Cassini curves for these distributed radar networks along with the Cassini curves of a monostatic radar system for the same level of received SNR, these benefits are graphically demonstrated. The SNR gains result in a much larger area of coverage for the distributed radar network compared to that of a power-equivalent monostatic radar. The impact of phase and pulse synchronization on a distributed radar network is also explored. By examining phase error and pulse error separately, and then examining their impact on the coverage areas of a two-node distributed radar network, the importance of synchronization to a distributed radar network is demonstrated. / US Marine Corps (USMC) author.

The study of complex systems and dynamical behaviors in disordered-coupled random Boolean networks

Hung, Yao-Chen 04 July 2006 (has links)
This paper investigates the complex systems and the dynamical behaviors in disordered-coupled random Boolean networks. In first part, we give a simple introduction to Kauffman¡¦s network and cellular automata, and apply them to study the virus dynamics and spatial distribution of ant lions. In the second part, a disordered coupling mechanism is introduced to study the dynamical behaviors (especially the synchronization phenomena) of random Boolean networks. Though the interactions between networks are microscopic, we formulate a macroscopic coupled model to describe the dynamics of the original system. The model tallies well with the original system. When the coupling strength exceeds the critical value, the coupling is sufficient to overcome the divergent nature of non-linearity and mutual synchronization is achieved. The finite size effect and different coupling configuration are also under our discussion.

Low-Complexity Timing and Frequency Offset Estimation Schemes for OFDM Systems

Wang, Shun-sheng 28 July 2006 (has links)
Two novel structures of training symbols are proposed for both timing offset and frequency offset estimations in orthogonal frequency division multiplexing (OFDM) systems. The first proposed training symbol has repeated sample blocks and a sign pattern on each block. With the proposed structure, system synchronization can be obtained with relatively low complexity. In particular, the frequency synchronization is accomplished using two successive stages to obtain both the fractional and integral parts of frequency offset with an estimation range of sub-carrier spacing. Simulation experiments demonstrate that the performance of the proposed scheme is substantially superior to the traditional schemes, or has negligible difference. The second proposed training symbol has the form of repeat and conjugate symmetric blocks and a sign pattern on each block. Then, a weighted timing metric is proposed to estimate the timing offset. Simulation results demonstrate that the proposed timing metric substantially improves the traditional schemes.


Alakhond, Sabah J., 1958- January 1986 (has links)
No description available.

Modeling Temporal Patterns of Neural Synchronization: Synaptic Plasticity and Stochastic Mechanisms

Zirkle, Joel 08 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Neural synchrony in the brain at rest is usually variable and intermittent, thus intervals of predominantly synchronized activity are interrupted by intervals of desynchronized activity. Prior studies suggested that this temporal structure of the weakly synchronous activity might be functionally significant: many short desynchronizations may be functionally different from few long desynchronizations, even if the average synchrony level is the same. In this thesis, we use computational neuroscience methods to investigate the effects of (i) spike-timing dependent plasticity (STDP) and (ii) noise on the temporal patterns of synchronization in a simple model. The model is composed of two conductance-based neurons connected via excitatory unidirectional synapses. In (i) these excitatory synapses are made plastic, in (ii) two different types of noise implementation to model the stochasticity of membrane ion channels is considered. The plasticity results are taken from our recently published article, while the noise results are currently being compiled into a manuscript. The dynamics of this network is subjected to the time-series analysis methods used in prior experimental studies. We provide numerical evidence that both STDP and channel noise can alter the synchronized dynamics in the network in several ways. This depends on the time scale that plasticity acts on and the intensity of the noise. However, in general, the action of STDP and noise in the simple network considered here is to promote dynamics with short desynchronizations (i.e. dynamics reminiscent of that observed in experimental studies) over dynamics with longer desynchronizations.


Qiu-Cheng, Xie, Zhong-Kui, Lei 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / In this paper, twelve optimum group synchronization codes (n=31 to 42) for PCM telemetry systems are presented. They are the newest achievements up to now.


Qiu-Cheng, Xie, Zhong-Kui, Lei 11 1900 (has links)
International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, twenty-four optimum group synchronization codes (N=31 to 54) for PCM telemetry systems are presented. These optimum codes are the newest development at the category of optimum group synchronization codes up to now in the world.

New advances in designing energy efficient time synchronization schemes for wireless sensor networks

Noh, Kyoung Lae 15 May 2009 (has links)
Time synchronization in wireless sensor networks (WSNs) is essential and significant for maintaining data consistency, coordination, and performing other fundamental operations, such as power management, security, and localization. Energy efficiency is the main concern in designing time synchronization protocols for WSNs because of the limited and generally nonrechargeable power resources. In this dissertation, the problem of time synchronization is studied in three different aspects to achieve energy efficient time synchronization in WSNs. First, a family of novel joint clock offset and skew estimators, based on the classical two-way message exchange model, is developed for time synchronization in WSNs. The proposed joint clock offset and skew correction mechanisms significantly increase the period of time synchronization, which is a critical factor in the over-all energy consumption required for global network synchronization. Moreover, the Cramer-Rao bounds for the maximum likelihood estimators are derived under two different delay assumptions. These analytical metrics serve as good benchmarks for the experimental results thus far reported. Second, this dissertation proposes a new time synchronization protocol, called the Pairwise Broadcast Synchronization (PBS), which aims at minimizing the number of message transmissions and implicitly the energy consumption necessary for global synchronization of WSNs. A novel approach for time synchronization is adopted in PBS, where a group of sensor nodes are synchronized by only overhearing the timing messages of a pair of sensor nodes. PBS requires a far smaller number of timing messages than other well-known protocols and incurs no loss in synchronization accuracy. Moreover, for densely deployed WSNs, PBS presents significant energy saving. Finally, this dissertation introduces a novel adaptive time synchronization protocol, named the Adaptive Multi-hop Timing Synchronization (AMTS). According to the current network status, AMTS optimizes crucial network parameters considering the energy efficiency of time synchronization. AMTS exhibits significant benefits in terms of energy-efficiency, and can be applied to various types of sensor network applications having different requirements.

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